Hi Paul,I like the idea of circulating through the block from head to head. I'll look on my 6v92 and see if it has obvious "plugs" to use for this purpose. I think if I add some valves to prevent cross flow of coolant when not using the webasto that this setup would not cause any cooling issues during the summer.

Brian I was worried about cross flow also as I am rigging up a heat exchanger loop past the webasto so I can heat the water in the electric water heater while driving down the road. or when parked open the loop and use the webasto to keep it warm. I called webasto and they confirmed the impeller on the pump in the unit is designed to allow water to pass by when the webasto is not in use. As I plan to circulate the water thru the webasto all the time and control my heaters thru loop controlled valves. Paul

Brian, I will second what Richard said about keeping your Detroit hot.

It will stay cleaner, be more efficient and last longer if run at 180 instead of 160. While the difference may not be drastic, there is nothing to be gained by running colder thermostats.

For comparison, check some of the modern engines, and find out what temperatures they are running them. In at least some cases, if it wasn't for the pressure cap, they would be boiling!

There has been some push to go to straight propylene glycol, which has a boiling point of something like 370 degrees F. While it has raised the coolant temperature some because of its lower specific heat, the operators have been claiming improved mileage with the increase in temperatures.

While it is expensive, it's supposed to be a one time cost, as the claim is that there is no corrosion and there is no bubble formation from operating too close to the boiling point. So, local overheating is supposed to be a thing of the past.

I have to agree with Tom & Richard on the lower thermostats. It is easy to fall into the thought process of lower thermostats will make it run cooler because of over heating issues, but it won't help with that. The thermostats 160 or 180 will be wide open (max flow) long before you start to overheat. The major down side to using to low a thermostat is just what Tom says. The engine performance and emissions will suffer during the times it doesn't have enough load on it to build the proper heat for efficent fuel burn.

I will have to look through all my bulletins, But I believe that DD sent one discontinuing using 160's in anything over the road.